Telecommunications switching networks traditionally have included SS7 signaling capabilities for communications over a telephone-signaling network. Such communications are primarily carried out utilizing a 64 kbits/s bearer channel that utilizes time division multiplexing (TDM,) and which is usually referred to as a narrowband network. This traditional switching network can be manufactured and supported by devices and systems such as the 5ESS® Switch which is manufactured by Lucent Technologies. A new generation of digital switching systems is evolving utilizing higher-bandwidth bearer channels and optical cable (OC) interfaces as the transmission medium to carry data and voice traffic. This new type of switch can provide significant bandwidth improvement, and is usually referred to as a broadband switch.
To inter-network bearer traffic between narrow and broadband switches, switch operators have begun utilizing transmission network elements to interface between narrowband (e.g., TDM) and broadband networks where the transmission network element requires no change to the narrowband switch transmission and signaling interfaces or procedures. At the same time, an on-going control information signaling standard, which is known as a Bearer Independent Call Control (BICC), and which is currently under development by the ITU standard committee and industry accepted procedures such as Internet Device Control Protocol (IPDC), can distribute and provide signaling, control and user information directly between narrowband and broadband network elements
FIG. 1 depicts a block diagram generally illustrative of a prior art telecommunication circuit switch network 100 associated with a switch office. Network 100 generally includes an administrative module 102, which can communicate with a communication module 104 that in turn can communicate with a switching module 106, a switching module 108 and/or a number of other switching modules, up to and including a switching module 192.
FIG. 2 illustrates a block diagram of the 64 kbps channel network for a prior art switching module 200, which can include a telephone line/trunk unit (LTU) 208 that communicates with a time slot Interface (TSI) 210 and a TSI 202. Switching module 200 can also include a LTU 206 that also can communicate with TSI 210 and a TSI 202. A digital line interface (DLI) 212 and DLI 204 can also be included in switching module 200 and can both communicate with TSI 202 and TSI 210. Through TSI 202 and 210, any of LTU 206, LTU 208, DLI 204 and DLI 212 can communicate with each other. TSI 202 and 210 provide duplicated paths between units as a part of the redundancy and reliability architecture of digital circuit switching module 200. In time division multiplexing and/or switching, the term “time slot” typically refers to a slot belonging to voice, data or video conversation, which can be occupied with conversation or simply left blank. The slot, however, always remains present. The capacity of the switch or transmission channel can be determined by keeping track of the number of slots present. A “time slot interface” or TSI is thus limited in the number of conversations it can support by the number of time slots it can interchange from one unit to another.
FIG. 3 depicts a block diagram of a prior art circuit switch telephone call path configuration 300. In this figure, the redundancy and reliability architecture of the digital switch is implicit. For example, TSI 328 in switching module 320 represents two physical TSI mechanisms that interconnect, for example, LTU 324 and DLI 326. As indicated in FIG. 3, a communications module 302 is composed of a switching fabric time-multiplexed switch (TMS) 304, which is generally associated with a link interface (LI) 306, and link interfaces 310, 312, and 314. Communications module 302 thus can communicate with prior art switching modules 320 and 330. Switching module 320 is composed of an LTU 324 and an LTU 322, which can communicate with a TSI 328, which in turn communicates with a DLI 326. Similarly, prior art switching module 330 includes an LTU 334 and an LTU 336, which communicates with a TSI 340, which in turn can communicate with a DLI 338. LTU 336 of switching module 330 can communicate with a terminal 344 (e.g., a telephone), while LTU 324 of switching module 320 can communicate with a terminal 342.
In general, a circuit switch provides a physical, dedicated path (i.e., time slot) for a call when it goes through the switching matrix. Because this path is dedicated to the call, no other callers can use that switch path until the call is ended. Since the call has an end-to-end dedicated circuit for the duration of the call, the switch is called a circuit switch. Circuit switching is used for voice switching and to support data services that have a constant bit rate (CBR). Circuit switching is called synchronous because the user's information is transmitted in a specific time slot, and only in that time slot.
Indeed, today's voice or telephone networks use this concept of a dedicated path, not just in the switch but through all transmission portions of the network as well. When a person places a voice call, a dedicated path is established through every switch and transmission line needed to connect the call before the person being called ever hears the telephone ring. This concept of a dedicated path guarantees high-quality, almost error-free transmission for the call. And since the average voice conversation is about three to four minutes long, network switch resources used to set up the path can be reused over and over during the course of the day.
Packet switches, in contrast, do not utilize dedicated paths. Packet switches originally were designed for data traffic that comes in bursts with a variable bit rate (VBR), so switching resources are shared, that is, assigned on an as-needed, first-come, first-served basis. When a burst of data comes in, resources are assigned for that burst. At the end of the burst of data, the resources are available for the next burst of data, regardless of the user. Since a customer's data can arrive at the switch at any time, packet switching is called asynchronous.
The present inventors have identified a number of problems with the prior art architectures and configurations discussed above. For example, a serious problem associated with the narrowband-broadband interface occurs with architectural changes from synchronous to asynchronous networks. The complexity of conversion for circuit-to-packet telephony or packet-to-circuit telephony within the domain of the network infrastructure, with no modification to existing digital circuit switches, can create unwanted interruption and unreliable services. The present inventors thus believe that the prior art telecommunications architectures and systems do not provide an adequate interface for narrowband and broadband communications and that improved telecommunication methods and systems are needed.